Characteristics of frontal plane lower limb movement during walking in patients with knee osteoarthritis of varying severity

Purpose: This study aimed to investigate the effect of knee joint structural destruction on frontal plane hip and ankle joint kinematics and kinetics during the stance phase of walking in patients with differing severities of knee osteoarthritis (KOA). Methods: An early KOA group consisted of eight subjects with bilateral knee Kellgren–Lawrence (KL) scale scores of 1 or 2. An established KOA group comprised nine subjects (18 knees) with KL scores of 3 or 4. To measure walking, the data were obtained using the motion analysis system and force plates. From the ground reaction force data, the stance phase of gait was divided into five periods. Results: In the established KOA group, the hip joint was significantly abducted, and the knee joint had significantly greater varus positioning during the stance phase. In addition, in the established KOA group, a significant knee abductor moment was observed during the stance phase. In contrast, in the early KOA group, the ankle joint showed a significant inversion moment during the stance phase, but in the established KOA group, the ankle joint moment was very small. Conclusions: The structural destruction of the knee joint in the frontal plane in patients with the established KOA changes the movement of the hip and the moment of the ankle.